This invention relates to the art of roll grooving apparatus and, more particularly, to improvements in such apparatus relating to obtaining and maintaining a desired alignment between grooving rolls and a workpiece and thus obtaining and maintaining tracking between the grooving rolls and workpiece so that the rolled groove is transverse to the workpiece axis.
The present invention finds particular utility in conjunction with a portable roll groover which is adapted to be interengaged with a rigidly supported pipe so as to travel about the periphery of the pipe during the roll grooving operation. Accordingly, while the invention will be illustrated and described herein in conjunction with such a roll groover, it will be understood and appreciated that the invention is applicable to roll grooving apparatus of the character wherein the roll groover is rigidly supported and the pipe to be grooved rotates relative thereto during the grooving operation.
Roll grooving apparatus is well known and generally includes a pair of relatively displaceable housing components or support members which respectively rotatably support a drive or back-up roll and an idler or grooving roll between which a pipe to be grooved is interposed during a grooving operation. The two rolls are matingly contoured and, in this respect, the drive roll is provided with a peripheral groove and the grooving roll is provided with a peripheral projection such that a pipe therebetween is provided with a peripheral groove upon relative rotation of the grooving rolls and relative radial displacement of the rolls toward one another. The drive roll is rotated by a hand tool or by a drive motor depending on the particular type of roll grooving apparatus.
Often, relative displacement between the roll supports is achieved through the use of threaded feed screw arrangements between the supports and which include a screw component which is manually rotated either by hand or by a tool such as a wrench. The roll supports are interengaged for linear or pivotal displacement toward and away from one another and, in either instance, the feed screw is rotated in the direction to separate the rolls to facilitate the insertion of the end of a tube or pipe therebetween, and the feed screw is then rotated in the opposite direction to bring the grooving rolls into engagement with the pipe. The pipe, back-up roll and grooving roll are then relatively rotated, and the feed screw is manually rotated in the direction to displace the grooving roll toward the back-up roll to progressively form a peripheral groove in the pipe. When the desired groove diameter is reached, relative rotation is stopped and the feed screw is rotated in the opposite direction until there is sufficient clearance between the two rolls to accommodate removal of the grooved pipe therefrom.
It is well known that it is necessary for the pipe and grooving roll axes to be properly aligned during a roll grooving operation so that the track of the groove is transverse to the pipe axis. Misalignment at the beginning of the roll grooving operation can cause the track of the groove to spiral relative to the pipe axis, whereupon the pipe or the tool xe2x80x9cwalksxe2x80x9d in the direction to axially separate the rolls and pipe. The tracking problem is attendant to the operation of any roll grooving apparatus including those in which the roll supports are relatively displaced other than by a feed screw and, for example, hydraulically as shown in U.S. Pat. No. 3,995,466 to Kunsmann, and manually through a pivotal lever arm as disclosed in U.S. Pat. No. 5,079,940 to Pulver, et al. Numerous efforts have been made to provide roll grooving apparatus with a self-tracking feature, and these efforts have included providing the back-up or drive roll with teeth on an outer surface thereof which urge the pipe and grooving rolls axially inwardly relative to one another as disclosed in U.S. Pat. No. 5,528,919 to McGrady, et al. Other efforts have included supporting the pipe to be roll grooved at an angle to the axes of the grooving rolls as disclosed in the aforementioned patent to Kunsmann, and by inclining the axis of the idler or grooving roll relative to the axis of the back-up roll as disclosed in U.S. Pat. No. 4,041,747 to Elkin and in U.S. Pat. No. 2,975,819 to Costanzo, et al. Still further efforts have included contouring the outer surface of the back-up or drive roll in the form of a frustum of a cone as disclosed in U.S. Pat. No. 5,279,143 to Dole, and by providing an auxiliary roller for engaging the outer surface of a pipe being grooved and having its axis inclined relative to that of a pipe being grooved as disclosed in the aforementioned patent to Costanzo, et al.
While all of the foregoing arrangements promote self-tracking, they add undesirably to the expense of the roll grooving apparatus by requiring additional and/or specially designed component parts for the apparatus, thus adding to the cost of maintaining the apparatus as well as the cost of manufacturing the same. Furthermore, in those devices using a feed screw for displacing the grooving rolls relative to one another, feed screw wear is often a problem as is the potential of jamming and a higher than desired input torque requirement. Moreover, there is a potential for damaging the feed screw through dropping of the roll grooving apparatus which is a common occurrence in the field. Still further, the forces required to groove thick wall pipe, such as 5 inch Sch. 40 pipe, cause the axis of the back-up or drive roll to deflect and thus adversely affect efforts to maintain proper tracking. Therefore, it has not been possible heretofore to roll groove a full range of pipe sizes from, for example, 1xc2xc inch to 12 inch, using just one basic grooving unit.
In accordance with the present invention, improvements are provided in roll grooving apparatus which minimize or overcome the foregoing and other problems encountered in connection with the structure and operation of roll grooving apparatus heretofore available. In accordance with one aspect of the invention, roll grooving apparatus of the character wherein the back-up and grooving roll supports are relatively displaced through the use of a feed screw is provided with features which improve the strength and life of the feed screw while easing wear thereof and increasing the torque capabilities thereof, thus promoting the ability to groove thick wall pipe. In part in this respect, the feed screw is pivotally interconnected at its opposite ends with the two roll supports and, thus, is direct acting with respect to the application of force on the feed screw in a manner which minimizes or eliminates side thrust encountered in connection with the use of some of the feed screw arrangements heretofore available. Another improvement in connection with the feed screw arrangement is a release mechanism by which one of the two support members is released for displacement relative to the feed screw in response to an impact such as that resulting from dropping the apparatus. With such apparatus heretofore available, the force of such impact is imposed directly on the threads of the feed screw and cooperatively threaded portions of the roll grooving apparatus, thus imposing wear and/or damage resulting in difficulty in rotating the screw, increased maintenance and replacement costs, and/or shortening of the useful life of the feed screw component.
In accordance with another aspect of the invention, improved tracking is achieved through the provision of one or more features relating to the structures of the back-up or drive roll and the grooving roll and the support of the two rolls in connection with the performing of roll grooving operations. More particularly in this respect, the back-up or drive roll is provided with a knurling arrangement which minimizes twisting of a pipe relative to the back-up and grooving rolls during a roll grooving operation. Another feature with respect to improving tracking resides in supporting the grooving roll for the axis thereof to be at a fixed angle to the axis of the back-up roll and, in connection with the roll grooving of certain pipe, providing a taper on the grooving projection of the grooving roll which promotes relative axial displacement of a pipe and the grooving rolls inwardly of one another during a roll grooving operation. Yet another feature in connection with improving tracking in accordance with the invention is the provision of a support for the axially outer end of the back-up roll to minimize deflection of the latter during roll grooving operations which involve the application of heavy forces against the back-up roll and which deflection precludes maintaining proper orientation or alignment between the two rolls and a pipe therebetween and, thus, loss of the desired tracking. The latter support feature also advantageously enables one basic roll grooving unit to handle a full range of pipe sizes from 1xc2xc inch to 12 inch diameter pipe, for example, whereas two or more different units were required heretofore to accommodate the roll grooving of such a full range of pipe sizes.
It is accordingly an outstanding object of the present invention to provide roll grooving apparatus of the character including a feed screw for relatively displacing the grooving and back-up rolls of the apparatus with improvements with respect to the application of forces against the feed screw during roll grooving operations.
Another object is the provision of roll grooving apparatus of the foregoing character with a feed screw arrangement which reduces wear of the screw, reduces jamming and reduces the required input torque in connection with roll grooving and improves the strength and longevity of the screw while enabling the roll grooving of thick wall pipe.
Yet another object is the provision of roll grooving apparatus of the foregoing character with an impact actuated release arrangement for protecting the feed screw and cooperatively threaded portions of the apparatus from damage resulting from an impact axially against the feed screw.
A further object is the provision of roll grooving apparatus with improved self-tracking capabilities.
Yet a further object is the provision of a back-up roll for roll grooving apparatus with a knurling arrangement for promoting tracking while minimizing the cost of achieving the same.
Still a further object is the provision of a grooving roll structure having improved self-tracking capability.
Another object is the provision of a grooving roll mounting arrangement providing improved self-tracking capabilities in roll grooving apparatus.
A further object is the provision of roll grooving apparatus with an arrangement for supporting the axially outer end of the back-up or drive roll against deflection resulting from the application of high roll grooving forces thereagainst.
Still a further object is the provision of a roll grooving unit capable of roll grooving a larger range of pipe sizes than possible with apparatus heretofore available.